I adjust for conditions. Especially if the trailer is heavier than the truck. If you get sideways from a panic maneuver, there's zero chance of coming back with that big anchor shoving the tail around. If traffic is dense, I'm going to keep room around me, even if it means slowing down. Watch how the big rig drivers do it. They seem to shoot for consistency and predictability. They may get close in packs, but notice how the packs drive, the best ones leave margin up front and don't jam the brakes and then take off. Your predictability lessens as you get more aggressive on it. On the open road, for me I also look at wind and other factors, including my level of fatigue. My tires are rated at 65, and that's generally about where I'll stay on the open interstate. I will not break the speed limit with a heavy load, as they seem pretty accurate for what I perceive the safety margin to be. I've had people pull on the road in front of me and panic stops are always an issue with a load, because the ABS is not as predictable, trailer brakes are not fine tuned devices, sharp steering swings a 5,000 lb pendulum around behind me, and even with load bars the braking balance is an unknown thing.
don't push it. is the extra 30 minutes worth the stress and aggravation?